Separate (9x^2 + 8x + 10)/(x^2 + 1)(x + 2) into partial fractions.

First, we find the form of the two fractions we're going to get. As one denominator has a power of 2, and the other a power of 1, our answer will be of the form: [(Ax+B)/(x2+1)] + [C/(x+2)]. If we make this our Right Hand Side, and make the question's equation our Left Hand Side, and then multiply by our LHS denominator, we get 9x2+8x+10=(Ax+B)(x+2)+C(x2+1). If we then set x = -2, to eliminate our Ax+B term, so that we can solve for C, our equation becomes 9(-2)2+8(-2)+10=C[(-2)2+1], Simplifying, we get 30=5C, and solve C=6. We then put this back into the initial equation we made and move the C fraction to the other side, we get (Ax+B)/(x2+1) = [(9x2+8x+10)/(x+2)(x2+1)] - [6/(x+2)]. We then make our RHS into one single fraction, by multiplying the latter fraction, top and bottom, by (x2+1). If we then simplify the numerator of our new RHS, we get (3x2+8x+4)/(x+2)(x2+1). We can factorise the numerator to give us (3x+2)(x+2), and find that the x+2 cancels out with the denominator. Now, our whole equation becomes (Ax+B)/(x2+1) = (3x+2)/(x2+1). Equating our coefficients of x, we find that A = 3, B = 2. So, our final solution is: (9x2+8x+10)/(x+2)(x2+1) = [(3x+2)/(x2+1)] + [6/(x+2)].

LU
Answered by Laura U. Maths tutor

3900 Views

See similar Maths A Level tutors

Related Maths A Level answers

All answers ▸

What is the chain rule?


Given x=Sqrt(3)sin(2t) and y=4cos^2(t), where 0<t<pi. Show that dy/dx = kSqrt(3)tan(2t).


What is a moment and how do I calculate it?


Show that the line with equation ax + by + c = 0 has gradient -a/b and cuts the y axis at -c/b?


We're here to help

contact us iconContact usWhatsapp logoMessage us on Whatsapptelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences